The present invention relates to a method for producing a coating of a pigment on a substrate.
There are several well known methods for producing coatings of pigments in powder form on a substrate having planar or spherically shaped surfaces. These methods include spraying, screen printing, sedimentation and the photo-optic method. Each of these methods is limited to special applications.
With spray methods, it is very difficult to obtain a homogeneous coating of uniform thickness over the entire surface area of an extensively structured surface. In particular, surfaces in the shadow of the spray cannot be satisfactorily coated.
Screen printing is limited to surfaces which are planar or curved in one direction only.
Sedimentation utilizes a force which acts predominently in one direction only. The thickness of the coating of the pigment substance will thus vary depending on the angle of inclination of the substrate surface.
The photo-optic method utilizes light to cross link a photo-lacquer. When the substrate surface to be coated has a surface configuration which causes light to strike the surface at different angles of incidence, different degrees of cross-linking of the photolacquer are produced.